What’s so unique about Obsession (US: The Hidden Room) is how Edward Dmytryk’s direction and Robert Newton’s performance use so much subtlety and restraint that we forget we’re watching a story of psychopathy and torture. Newton (under)plays Dr. Clive Riordan, a wealthy psychiatrist who discovers that his younger, fantastically named wife Storm (Sally Gray) has been having an affair with American Bill Kronin (Phil Brown) and responds in an unexpectedly cool and calm manner: he enacts the “perfect murder,” which involves kidnapping Kronin at gunpoint and locking him away for months in a dark, inaccessible room while Riordan develops an acidic substance that will dissolve Kronin’s corpse completely when the time comes. Easy peezy! Such ugliness is softened not only by the British propriety and wit but by the expressionist lighting which follows Riordan each time he visits his captive in the Gothic London ruins and shadowy cobblestone streets. Naunton Wayne plays police inspector Finsbury, who catches a whiff of suspicion when questioning the Riordans and doggedly pursues the case, reminding Riordan that even the savviest killer is always caught. The film is far from action-packed; on the contrary, the pacing is slow and deliberate, Riordan’s massive toy train set symbolizing his desire to control his world down to the smallest detail. Given that the source novel (and play) was titled A Man About a Dog, it shouldn’t be surprising that the little dog named Monty will play an outsized role in the resolution of the story.